I have to say D, either are sufficient.
Given: Store sells only half and qtr gallon cartons of milk. 300 Cartons were sold. We need to know how many of one type was sold to solve for the other.

1) Since 300 were sold, 120 were qtr gal, the other 180 were half gal
2) tells us that 180 half gal cartons were sold (90 Gallons of milk from half gallon cartons), the other 120 must have been qtr gallons.

Unless the question is pulling some kind of BS like the cartons aren't full or something, in which case, it's not a question worth working on, imho.

should be d.

x*0.5 + y*0.25 and x+y=300.

stat 1 tells us y, and we can figure out x, and therefore total amount of milk

stat 2 tells us x, and we can find y and therefore total amount of milk

300=x+y

1: we know y so we can figure out x. Thus we can figure out the amount of gallons

2: .5x=90 --> x=180 cartons We can find y b/c we know x


D

I'm getting different answers when I solve to prove its D can someone please provide detailed explanation with equations! thanks

Nq - Number of quarter gallon cartons sold
(300 - Nq) - Number of half gallon cartons sold

Gallons of milk sold = Nq*(1/4) + (300 - Nq)*(1/2)

1. yesterday the store sold 120 one-quarter-gallons of milk.
I assuming that they meant '120 one-quarter-gallon cartons of milk'.

So Nq = 120. So, Nh = 180
Gallons of milk sold = 120*(1/4) = 180*(1/2)


2. Yesterday the store sold 90 gallons of milk in one-half-gallon cartons.

(300 - Nq)*(1/2) = 90
300 - Nq = 180
Nq = 120

Gallons of milk sold = 120*(1/4) = 180*(1/2)
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Must read the question carefully unlike I did, initially.

The store sells two size of milk cartons, one-half gallon and one-quarter gallon cartons. Yesterday, they sold 300 cartons of milk in total.

Stem: wants to know how many gallons of milk were sold, so we must be given the part to whole or part to part ratio of types of gallons sold.
Provides that:Q+H=300 cartons

1. 300 cartons=120+H
H=180, sufficient. 180*.5=90 120*.25=30
Gallons sold=120.

2.90 gallons sold in 1/2 gallon cartons, so 180 half-gallon cartons were sold. This tells us that: 300=Q+180, so Q=120 cartons. 120*.25=30 gallons
sufficient

Each statement alone is sufficient, D.

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